Process for the manufacture of iron-leather



ocrro Roma, or nenms'ranr, canny.

PROCESS FOR THE MANUFACTURE OF IRON-LEATHER.

No Drawing.

To all whom it may concern:

Be it known that I, O'r'ro RoHM, a citizen of the Free State ofWurttemberg, in the German Republic, residing at Darmstadt, in the Stateof Hessia, Germany, have invented Improvement in and Relating to aProcess for the Manufacture of Iron- Leather, (for which I have filedapplications in Germany May 2, 1918; in Czechoslovakia Aug. 19, 1919; inAustria Nov. 22, 1919; in Hunga Nov. 28, 1919; andin Spain March 30,1920;). and I do hereby declare the following to be a fullfclear, andexact descrlption of the same.

My invention relates to a process for tawing or alutation of skins bymeans of silicate of iron, in which the skins are acted upon bysolutions of iron salts and silicates together,

i. e. in a single tawing bath.

Hitherto for the manufacture of ironleather soluble iron salts forinstance basic sulfate of iron or basic ferric chlorid have been used.It has also been proposed to first taw the skins with soluble iron saltsand then to ut the iron-leather thus obtained in a so ution containing(besides sebacic combinations) alkaline silicate. In proceeding in thisway a part of the iron salt taken up by the skin is first precipitatedagain and celerated manner.

forms with the alkaline silicate an insoluble silicate of iron. Thelatter settles upon the skin which'thereby becomes brittle.

According to the new process the skin is acted upon by the silicate ofiron during the colloidal state whereby a non brittle iron-leather isobtained in a simple and ac- To this end the skins during tawing withiron salts are brought together with diluted solutions of waterglass.

If in carrying out this process a concentrated Solution of water-glassof 36 B. would be added to a solution of an iron salt, such as ferricchlorid, a separation of insoluble'silicate of iron would take place atonce and a tawing with this mixture would be impossible. If however theconcentrated solution of water-glass is first diluted for instance withan 810 fold quantity of water and said solution of waterglass added tothe solution of ferric chlorid, a separation of silicate of iron doesnot take place even it up to 4 parts of water-glass a17e added to onepart of ferric-chlorid. Moreover the deposit of silicate ofironSpecification of Letters Patent.

Patented Nov. 15, 1921.

Application filed July 9, 1920. Serial No. 395,146.

formed at the be inning of the process is perfectly dissolvef again onstirring.

The solutions of sllicate of iron thus obtamed are, as stated above,especially adapted for the manufacture of ironleather. Against solutionsof basic iron salts the said solutions of silicate of iron have theadvantage that they very easily penetrate the skin or in other-word veryquickly taw.

The lnvention may also be carried out in such a manner that the skin isfirst brought into the solution of iron salt and after the latter haspenetrated the skin the desired quantity of solution of water-glass isslowly added to the same bath.. In this way also the forming ofinsoluble silicate of iron is prevented.

It has already been stated above that according to the new process up to4 parts of water-glass may be used with 1 part of iron salt. Dependingupon the proportions used leather of different properties is obtainedand the more water-glass'is used in proportion to the iron salt thefuller and stronger the leather.

To obtain iron-leather by means of silicate of iron one of the followingprocesses may be used: 7 1

1. To taw 100 kg. of skins a clear solution of silicate of iron isprepared by adding a diluted solution of water-glass to a solution of 10kg. ferric chlorid in 100 1. water. solution of concentrated water-glasis added and with this mixture the skins are tawed, washed out, fattedif necessary, dried and dressed in a well known manner.

2. 100 kg. of skins are first placed in a solution of 10 kg. of ferricchlorid and 5 kg. of common salt in 100 1. water. After. some time200-300 kg. of a 10% solution of waterglass are slowly? added to theconstantly moving tawing bath. The moving is continued until the skindoes not take up any more tawing matter. taken out, washed out withwater, fatted if necessary, dried and dressed.

To further improve the properties of the iron-leather thus obtained thesame measures may be taken as are used in the other tawing 105 a tawmgby means of formaldehyde, Ac- 110 For instance 200-300 kg. of a 10% Theleather is then cording to the present process also the tawing actionwill be improved by the use of aldehydes for instance formaldehyde and aspecially resistant leather is obtained. The aldehyde may be addedduring any desired stage of the process, z'. 6. before, during or afterthe tawing explained above.

If these improvements are to be used 2-3 kg. of formaldehyde may beadded to the example of the quantity of water-glass given above for thetawing of 100 kg. of, skins. The formaldehyde tawing may however takeplace before or after the tawing with iron salts.

It may also be stated that before the tawing the skins may be pickled asis usual in tawing with chrome salts. Also the pickling: acid may beadded to. the salt :solut1onsdescribed above. By the use of acid in thisform the tawing is accelerated and a specially Smooth grain is obtained.9-

Having-now described and ascertained'the' nature of my invention and themanner in which the same is to be performedInow declare what I claim anddesire to secure by Letters Patent of [the United. States is 1. Theherein described process for manufacturing iron-leather, consisting insubjecting the skins to a solution ofiron'salts, and

adding a diluted solutionofwater glass' 'to said solution.

name to this specification in the a two subscribing witnesses.

2. The herein described process for manufacturing iron leather,consisting'in subjecting the skins to a solution of iron salts andfacturing iron leather, consisting in subjecting the skins to. a tawi'ngsolution of iron salts, adding a diluted solution of water glass tothetawing solution, and adding a solutionof formaldehyde to the tawingsoluti0n.-- V

i 5. The herein described process for manufacturing iron-leather,consisting in sub- 1 je'ctingz'the skins to a solution of iron salts,.an'dijadding to said solution ,a solution of water. glassandformaldehyde.

-Intestimony whereof, I have signed my presence of DR. OTTO. R'O'HM.

.v v WILBEIMIYANDRESL

